How to make it dark

I have just started to make a slender game. I am using a spotlight as a flashlight, but the world is not dark enough without it.
when I turn it off, I can still see everything around me very clearly. Is there a way to make it darker?

Set the render settings.

In Unity, navigate to Edit > Render Settings

Enable (tick) the box that says Fog.

Click the Fog Colour box, set the ambient light to 29 on each of the RGB sliders. You can see the change in the scene, pick a colour that is dark but not pitch-black.

Click the Ambient Light Colour box, set the ambient light to 51 on each of the RGB sliders. You can see the change in the scene. Again, pick a colour that is dark but not pitch-black.

May be this can help you. This article is in Russian, but you can see pictures and if you’ll like it you can get shader here