How do I make this Camera movement happen when I right click?

This allows me to rotate and move the camera when I move my mouse fine but I want to make it move only when I right click and move around the mouse

using System.Collections; using System.Collections.Generic; using UnityEngine;

 public class TestCam : MonoBehaviour {
 
     //All the variables used in this class(Look below to see what they do. :D   )
     private const float Y_ANGLE_MIN = 0.0f;
     private const float Y_ANGLE_MAX = 50.0f;
     private const float DISTANCE_MAX = 5.0f;
     private const float DISTANCE_MIN = 0.1f;
     private const float TRANS_MIN = 1.0f;
     private const float TRANS_MAX = 2.0f;
 
     public Transform lookAt;
     public Transform camTransform;
     public GameObject player;
 
     private Camera cam;
 
     public float distance = 5.0f;
     private float currentX = 0.0f;
     private float currentY = 0.0f;
     private float sensitivityX = 4.0f;
     private float sensitivityY = 1.0f;
     private float trandis;
 
     public Vector3 height = new Vector3(0, 0, 0);
 
     private bool below = false;
 
     private void Start()
     {
 
         //Makes camTransform a transform. :)
 
         camTransform = transform;
         //Sets variable cam value to the main camera
         cam = Camera.main;
 
     }
 
     private void Update()
     {
 
         //Makes the camera move by looking at the axis of the mouse(Also multiplied by the seisitivity.)
 
             currentX += Input.GetAxis ("Mouse X") * sensitivityX;
             currentY += Input.GetAxis ("Mouse Y") * sensitivityY;
 
         //Limits the Y variable
         currentY = Mathf.Clamp(currentY, Y_ANGLE_MIN, Y_ANGLE_MAX);
 
         //Thiago Laranja's scrollwheel implemetation.
         if (Input.GetAxis("Mouse ScrollWheel") > 0) { distance += 0.2f; }
         if (Input.GetAxis("Mouse ScrollWheel") < 0) { distance -= 0.2f; }
 
         //Makes sure that these variables never go over the max and be les than the min. :)
         distance = Mathf.Clamp(distance, DISTANCE_MIN, DISTANCE_MAX);
         trandis = Mathf.Clamp(distance, TRANS_MIN, TRANS_MAX) - 1;
 
         //Sets players transparency(Make sure that player materials rendering mode has set to transparent or other mode that supports transparency).
         player.GetComponent<Renderer>().material.color = new Color(player.GetComponent<Renderer>().material.color.r, player.GetComponent<Renderer>().material.color.g, player.GetComponent<Renderer>().material.color.b,trandis);
 
         //Disables the object from rendering if your're at distance 0.8.
         if (distance <= 0.8f) { player.GetComponent<Renderer>().enabled = false; }
         if (distance > 0.8f) { player.GetComponent<Renderer>().enabled = true; }
 
         //If close enough to the character sinp into distance of 0.1(If distance is 0 the camera cant be rotated.)
         if (distance <= 0.8f && below == false) { distance = 0.1f; below = true; }
         if (distance >= 0.8f && below == true) { below = false; }
         
     }
     private void LateUpdate()
     {
 
         //Subtracts hte distance from Z coordinate
         Vector3 dir = new Vector3(0, 0, -distance);
 
         //Creates an quaternion for rotation(too bad that we cannot use Vector3. :D   )
         Quaternion rotation = Quaternion.Euler(currentY, currentX, 0);
 
         //Sets the cameras position and makes it look at player.
         camTransform.position = lookAt.position + height + rotation * dir;
         camTransform.LookAt(lookAt.position + height);
 
     }
 
 }