Help change the subject of this Script

i have a script that instaniate an object for examlpe a “cube” from the project to spawn at the mouse position

i want to change to make the script " move an already exist in the hierarchy to the mouse position
NOTE : “not creating new one of it” “just moving an already exist object in the hirarchy to the mouse position”

i hope i presented my proplem well for anyone wants to help here is the script

using UnityEngine;
using System.Collections;

public class InstantiateAtMousePosition : MonoBehaviour {

	Vector3 mousePosition,targetPosition;

	//To Instantiate TargetObject at mouse position
	public Transform targetObject;

	float distance=10f;

	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {

		//To get the current mouse position
		mousePosition=Input.mousePosition;

		//Convert the mousePosition according to World position
		targetPosition=Camera.main.ScreenToWorldPoint(new Vector3(mousePosition.x,mousePosition.y,distance));

		//Set the position of targetObject
		targetObject.position=targetPosition;

		//Debug.Log(mousePosition+"   "+targetPosition);


		//If Left Button is clicked
		if(Input.GetMouseButtonUp(0))
		{
			//create the instance of targetObject and place it at given position.
			Instantiate(targetObject,targetObject.transform.position,targetObject.transform.rotation);	
		}
	}
}

You could make a public GameObject variable for the target object, then drag in the target object from the heirarchy to the script, then on line 38 instead of Instantiate set the target objects position to the target position and rotation to target rotation etc…