How do I add a pulling force?

Hey! Not sure how your code looks like, but off the top of my head I have 3 possible solutions that may work.
1. Make the object you want you 'pull' a child of the pulling object. A child will move as one with its parent.
2. Use Vector2.MoveTowards.
3. Add force in the desired direction.

//Set parent.
if (Input.GetKeyDown(KeyCode.X))
{
transform.SetParent(pullingObject.transform);
}
//In order to detach a child from a parent
if (Input.GetKeyUp(KeyCode.X))
{
transform.SetParent(null);
}

//Vector2.MoveTowards. Should be place in a FixedUpdate/Update.
if (Input.GetKeyDown(KeyCode.X))
{
transform.position = new Vector2.MoveTowards(transform.position, pullingObject.transform.position, speed)
}

//Add force in desired direction.  
//Negative X to move left, negative Y to move down.
//Move left for example:
transform.GetComponent< Rigidbody2D>().AddForce(new Vector2(-5f, 2f));