How to make a retracting Tongue?

I've been messing around with the 2D controls in Unity, and have successfully coded a tongue to translate vertically in the Game, but am wondering how to make it retract after some time (1-2 seconds). Similarly, I've had trouble implementing a "power bar" system, where the distance that the tongue reaches is depending on the duration of the button press.

Here is my code (javascript):

 #pragma strict
 
 function Start () {
     transform.position.z = -0.5;
 }
 
 function Update () {
     if(Input.GetKeyDown ("space"))
     {
         moveTo(transform.position.y + 11.8, 20); // Feed the moveTo() function the X/Y positions you want to move it to, and the Speed you want to move at
     }
     transform.position.z = -0.5;
 }
 
 function moveTo(posY : float, speed : float)
 {
     while (transform.position.y != posY)
     {
         transform.position = Vector2.MoveTowards (transform.position, new Vector2(transform.position.x, posY), speed * Time.deltaTime);
         yield;
     }
 }

Thanks, any help is appreciated.