Input.GetMouseButton

설명

Returns whether the given mouse button is held down.

button values are 0 for left button, 1 for right button, 2 for the middle button.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    void Update() {
        if (Input.GetMouseButton(0))
            Debug.Log("Pressed left click.");
        
        if (Input.GetMouseButton(1))
            Debug.Log("Pressed right click.");
        
        if (Input.GetMouseButton(2))
            Debug.Log("Pressed middle click.");
        
    }
}