// Detects if any key has been pressed.

function Update() {
    if(Input.anyKey)
        Debug.Log("A key or mouse click has been detected");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Update() {
        if (Input.anyKey)
            Debug.Log("A key or mouse click has been detected");
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Update():
        if Input.anyKey:
            Debug.Log('A key or mouse click has been detected')