unity how to check if the mouse clicks on an object code example

Example 1: how to detect a mouse click in unity

using UnityEngine;
using System.Collections;

		if (Input.GetMouseButtonDown(0)) {
        	//Left Mouse Button
        } else if (Input.GetMouseButtonDown(1)) {
        	//Right Mouse Button
        } if (Input.GetMouseButtonDown(2)) {
        	//Middle Mouse Button
        }

Example 2: unity check when clicked on object

void Update()
{
  // Check for mouse input
  if (Input.GetMouseButton(0))
  {
  	Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
   	RaycastHit hit;
   	// Casts the ray and get the first game object hit
   	Physics.Raycast(ray, out hit);
   	Debug.Log("This hit at " + hit.point );
  }
}