How to make object solid with Vector3.MoveTowards?

I have a sphere which moves to my mouse position when I click on the screen. I also have a cube, now I can move trough the cube, but I want the cube is solid so I can`t move trough it. This is my code:

 public bool canMove = false;
 public Vector3 endPoint;
 public float duration = 50f;
 void Update(){
   if(Input.GetMouseButton(0)){
     canMove = true;
     endPoint = Input.mousePosition;
     endPoint.z = transform.position.z = Camera.main.transform.position.z;
     endPoint = Camera.main.ScreenToWorldPoint(endPoint);
   }
   if(transform.position == endPoint){
     canMove = false;
   }else if (canMove){
     transform.position = Vector3.MoveTowards(transform.position, endPoint, duration * Time.deltaTime);
   }
 }

How can I make the cubes solid so I can`t move trough it?

Sorry for bad formulated question.