How to aim the flashlight with the mouse in a 2d game?

I am working on a 2D platformer-ish game and I want to be able to move the mouse and have the spotlight follow the mouse so the player can control which direction the flashlight is pointing. I've been trying to figure it out for the last 2 days but I still have no idea where to start. Does anybody know how to do this?

Edit:

Maybe I should have included my script, even though all it does is turn off the flashlight. I don't know what I'm doing wrong.

 var mousePos : Vector3;
 
 function Start () {
     mousePos = Input.mousePosition;
 }
 
 function Update () {
     transform.rotation = Quaternion.LookRotation(mousePos);
 }