How Change one object to another in animation? ( change Sphere to cube)

Hi people. I am new in game development . So I am trying to change Sphere to Cube during the animation I wrote this code, but it has lots of problems and I can't find mistakes . I create one empty object as a parent and cube and sphere as a circle . I don't know its right or not also in all of them add this script. And it does not work . Could U help me plz ? using UnityEngine; using System.Collections;

public class Replaceobjects : MonoBehaviour {

  public Transform Sphere;
  public Transform Cube;
  
  
  private Transform clone;
 
  
  void Start () {
  
  }
  
  void Update () {
  
  }
  
  
  {
      Vector3 clonePosition = new Vector3( 0.6096257f, 0.002073564f, -1.967801f );
      
      switch( Random.Range(0, 2) )
      {
         case 0 :
              clone = Instantiate( Sphere, clonePosition, Quaternion.identity) as Transform;
         break;
  
         case 1 :
              clone = Instantiate( Cube, clonePosition, Quaternion.identity) as Transform;
         break;
      }
  
      Destroy( gameObject );
  }
  

}