Access another object's variable

I'm trying to access a specific variable in a script attached to another gameobject. I have no idea how to do this. Does anyone else know? using UnityEngine; using System.Collections;

 public class StandardAttacksP1 : MonoBehaviour {
 
     public GameObject controllerDetect;
     public Component controllers;
 
     void Start () {
         controllers = controllerDetect.GetComponentInChildren<ControllerAmountDet> ();
     }
 
     void Update () {
         if (controllers.playerOneKeyboard == true) {
             //Do something
         }
     }
 }