ClickToLoad.cs

using UnityEngine;
using System.Collections;
using UnityEngine.SceneManagement;

public class ClickToLoad : MonoBehaviour {


    public void loadLevel(string nextLevel) {

        StartCoroutine(DisplayLoading(nextLevel));

    }

    IEnumerator DisplayLoading(string nextLevel) {

        // assigning Async task
        AsyncOperation async = SceneManager.LoadSceneAsync(nextLevel);

        // while async is running
        while (!async.isDone) {
            Debug.Log(async.progress);

            yield return null;

        }

    }

}