How do i change the crosshair when i pick up a object

i want to make a game with a portalgun and i want the crosshair to change when i drop and pickup the portal gun

using UnityEngine.UI;

public class ChangeCrosshairs
{

 public RawImage crosshairs;

public Texture one;
public Texture two;

public void Change()
{

crosshairs.texture = two;

}

}