Profiler.BeginSample ("MyPieceOfCode");
    // do something that takes a lot of time
    Profiler.EndSample ();

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        Profiler.BeginSample("MyPieceOfCode");
        Profiler.EndSample();
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        Profiler.BeginSample('MyPieceOfCode')
        Profiler.EndSample()