Touch area binding

I have created a button in my 2d game using Unity3d, added box collider 2d with name PADBASE to detect touch events this way:

 if(Input.touchCount > 0)
 {
     for(int i = 0; i < Input.touchCount; i++)
     {
         Vector3 mouseWorldPos3D = Camera.main.ScreenToWorldPoint(Input.GetTouch(i).position);
         Vector2 mousePos2D = new Vector2(mouseWorldPos3D.x, mouseWorldPos3D.y);
         Vector2 dir = Vector2.zero;
         RaycastHit2D hit = Physics2D.Raycast(mousePos2D, dir);
         Touch t = Input.GetTouch(i);
         
         if (hit.transform != null)
         {
             if(Physics2D.Raycast (hit.transform.position , hit.transform.forward))
             {
                 GameObject recipient = hit.transform.gameObject;
                 
                 if(t.phase == TouchPhase.Began) //poczatek dotyku
                 {
                     // button clicked
 
                     // change colour to red to visually show that button is being pressed
                 }
                 else if (t.phase == TouchPhase.Ended)
                 {
                     // change collor to its default colour to visually show that its no longer pressed
                 }
             }
 
         }
     }
 }

And lets assume I will change button colour to red when player touched the button, and back to its default colour when he released his finger (for example)

Now it will obviously work only when player will release his finger, as long as his finger is actually inside bounds of the box collider, what I am trying to do is "bind touch events(?)" to still catch touch event (slide or ended) even if player moved his finger outside of the collider without releasing his finger (for example accidentally)

I am looking forward for some suggestions, thanks.

In my game I will have multiple buttons so multi touch is necessary.