Unity2D: how to move an object within a certain collider ?

Hi. I’m making a game where you have to drag an object from one point to another. Started to do on the principle of games with a puzzle, but there the object is attached to a certain point, but I need the player can choose in which point of the collider, leave the object.

Use an edge collider, so the object will collide with the border of the designated area.