How can I drag an object at specific distances?

Hello Im trying to make the red circle levers move in certain Y distances

I tried something like this but; . public class DragObject : MonoBehaviour {

 public GameObject Lever;
 Vector2 leverPos, currentLevPos;
 float distanceY;
 private void FixedUpdate()
 {
     currentLevPos = transform.position;
     leverPos = Lever.transform.position;
     distanceY = Mathf.Abs(currentLevPos.y - leverPos.y);
 }
 void OnMouseDrag()
 {
     if (distanceY<=0.5 && distanceY>0)
     {
         Vector2 curPosition = Camera.main.ScreenToWorldPoint(Input.mousePosition);
         transform.position = new Vector2(transform.position.x, curPosition.y);
         
     }       
 }

} It stays at the distance that I want, but then I cannot move my object Is there any better solution for this ?