Execute any code based on Unity events without having to drag a component into a scene.

MyStaticCode.cs

using UnityEngine;

/// <summary>
/// This template allows to define code that runs independently of any GameObjects or Components created in the editor, even though using Unity events.
/// It can be used for any Scene-independent code, including coroutines, without having to manually add a component to a scene.
/// </summary>
public static class MyStaticCode
{
    [RuntimeInitializeOnLoadMethod]
    private static void Initialize()
    {
        var go = new GameObject("MyStaticCode");
        go.AddComponent<Worker>();
        go.hideFlags = HideFlags.HideAndDontSave;
        Object.DontDestroyOnLoad(go);
    }

    private class Worker : MonoBehaviour
    {
        private void Update()
        {
            Debug.Log("What's up?");
        }
    }
}