MouseController.cs

using UnityEngine;
using System.Collections;

public class MouseController : MonoBehaviour
{

	Ray ray;
	RaycastHit hit;
	public GameObject prefab;



	void Update ()
	{
	
		ray = Camera.main.ScreenPointToRay (Input.mousePosition);

		if (Physics.Raycast (ray, out hit)) {
			if (Input.GetKeyDown (KeyCode.Mouse0)) {
				Debug.Log ("Left Mouse Down");

				GameObject obj = Instantiate (prefab, new Vector3 (hit.point.x, hit.point.y, hit.point.z), Quaternion.identity) as GameObject;
			}
			if (Input.GetKeyDown (KeyCode.Mouse1)) {
				Debug.Log ("Righ Mouse Down");
				Destroy(hit.transform.gameObject);
			}
		}
	}
}