UI: On pointer down enter detection

Hello, I am currently struggling with this.

How to detect OnPointerDown when it enters other ui element?

I want to make that when user presses shoot (number 1) and drags finger to joystick (number 2), joystick detects the finger, rotates player object and also continues to shoot at the same time?

I am using Unity Joystick.cs

 using UnityEngine;
 using UnityEngine.EventSystems;
 using UnitySampleAssets.CrossPlatformInput;
 
 public class Joystick : MonoBehaviour , IPointerUpHandler , IDragHandler, IPointerDownHandler  {
 
     public int MovementRange = 100;
 
     public enum AxisOption
     {                                                    // Options for which axes to use                                                     
         Both,                                            // Use both
         OnlyHorizontal,                                  // Only horizontal
         OnlyVertical                                     // Only vertical
     }
 
     public AxisOption axesToUse = AxisOption.Both;   // The options for the axes that the still will use
     public string horizontalAxisName = "Horizontal"; // The name given to the horizontal axis for the cross platform input
     public string verticalAxisName = "Vertical";     // The name given to the vertical axis for the cross platform input 
 
     private Vector3 startPos;
     private bool useX;                         // Toggle for using the x axis
     private bool useY;                         // Toggle for using the Y axis
     private CrossPlatformInputManager.VirtualAxis horizontalVirtualAxis;      // Reference to the joystick in the cross platform input
     private CrossPlatformInputManager.VirtualAxis verticalVirtualAxis;        // Reference to the joystick in the cross platform input
    
     void OnEnable () 
     {
         CreateVirtualAxes ();
     }
     
     
     
     void Start ()
     {
        startPos = transform.position;
     }
 
     private void UpdateVirtualAxes (Vector3 value) {
 
         var delta = startPos - value;
         delta.y = -delta.y;
         delta /= MovementRange;
         if(useX)
         horizontalVirtualAxis.Update (-delta.x);
 
         if(useY)
         verticalVirtualAxis.Update (delta.y);
 
     }
 
     private void CreateVirtualAxes()
     {
         // set axes to use
         useX = (axesToUse == AxisOption.Both || axesToUse == AxisOption.OnlyHorizontal);
         useY = (axesToUse == AxisOption.Both || axesToUse == AxisOption.OnlyVertical);
 
         // create new axes based on axes to use
         if (useX)
             horizontalVirtualAxis = new CrossPlatformInputManager.VirtualAxis(horizontalAxisName);
         if (useY)
             verticalVirtualAxis = new CrossPlatformInputManager.VirtualAxis(verticalAxisName);
     }
 
 
     public  void OnDrag(PointerEventData data) {
 
         Vector3 newPos = Vector3.zero;
 
         if (useX) {
             int delta = (int) (data.position.x - startPos.x);
             newPos.x = delta;
         }
 
         if (useY)
         {
             int delta = (int)(data.position.y - startPos.y);
             newPos.y = delta;
         }
         transform.position = Vector3.ClampMagnitude( new Vector3(newPos.x , newPos.y , newPos.z), MovementRange) + startPos;
         UpdateVirtualAxes (transform.position);
     }
 
 
     public  void OnPointerUp(PointerEventData data)
     {
         transform.position = startPos;
         UpdateVirtualAxes (startPos);
     }
 
     public  void OnPointerDown (PointerEventData data) 
     {
         OnDrag(data);
     }
 
 
 
     void OnDisable () {
         // remove the joysticks from the cross platform input
         if (useX)
         {
             horizontalVirtualAxis.Remove();
         }
         if (useY)
         {
             verticalVirtualAxis.Remove();
         }
     }
 }