Simple example showing how to use the Screencapture class.

ScreencapScript.cs

/// <summary>
/// Attach this script to any gameobject in the scene, enter Play Mode, then hit Space on your keyboard to capture a screenshot.
/// Exit Play Mode, refresh the Project panel, and the scenecap image should be in the Assets folder.
/// </summary>
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ScreencapScript : MonoBehaviour {

	// Use this for initialization
	void Start () {

	}
	
	// Update is called once per frame
	void Update () {
		
		if(Input.GetKeyDown(KeyCode.Space))
		{
			ScreenCapture.CaptureScreenshot(Application.dataPath + "/screencap.png");
		}
	}
}