Check out example codes for "onmouseover unity". It will help you in understanding the concepts better.

Code Example 1

//Attach this script to a GameObject to have it output messages when your mouse hovers over it.
using UnityEngine;public class OnMouseOverExample : MonoBehaviour
{
    void OnMouseOver()
    {
        //If your mouse hovers over the GameObject with the script attached, output this message
        Debug.Log("Mouse is over GameObject.");
    }    
    void OnMouseExit()
    {
        //The mouse is no longer hovering over the GameObject so output this message each frame
        Debug.Log("Mouse is no longer on GameObject.");
    }
}

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