Get GameObject That Was Last Clicked?

Simply use a variable named something like "lastClicked". The way I have the raycast here isn't how people usually do it. The way I have it, only updates the ray on mouse click, instead of every frame.

 using UnityEngine;
 using System.Collections;
  
 public class Example : MonoBehaviour
 {
     GameObject lastClicked;
     Ray ray;
     RaycastHit rayHit;
  
     void Update()
     {
         if(Input.GetMouseButtonDown (0))
         {
             ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             if(Physics.Raycast(ray, out rayHit))
             {
                 lastClicked = rayHit.collider.gameObject;
                 if(lastClicked != null)
                     print(lastClicked.name);
             }
         }
     }
 }