Wait for a while before executing the code c#

I'm trying to make my medal go back to its original after it has been brought into the scene

The following code below shows the medal being brought in the scene but I am unable to let it slide back to its original position after awhile, approximately 5 seconds after it entered the screen.

  void OnMouseDown ()
 {
     
     if (tag == "giveChange") 
     {
         if (Customer.cashChange.ToString () == Background.correctChange.ToString ()) 
         {
             correctAns++;
             if (correctAns == 1) 
             {
                 

                     startMarker = medal.position;
                     endMarker = medal.position - new Vector3 (0, 8, 0);
                     journeyLength = Vector3.Distance (startMarker, endMarker);

                 
             }                 
         }
     }

}