Follow the mouse

How can I make an object follow the mouse in a certain area, and after the mouse leaves the area, the object remains at the edge of the area. When the mouse re-enters the area, the object should follow the mouse again. This is the code at the moment:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class FollowMouse : MonoBehaviour
 {
     private Vector3 mousePosition;
     public float moveSpeed = 0.1f;
   
     void Update()
     {
         
         
             mousePosition = Input.mousePosition;
             mousePosition = Camera.main.ScreenToWorldPoint(mousePosition);
             transform.position = Vector2.Lerp(transform.position, mousePosition, moveSpeed);
         
 
     }
 }