Fallout 4 Sinister Ambient Sounds mod. (PC/Xbox mod)
This creepy mod does NOT add new creatures, but instead adds loads of Ambient creature noises into the soundscape, so as you travel the wastelands you will now hear screeches, screams, growls, howls and gurgling alongside the regular birds and distant gunshots/explosions, and if you use the night version, it'll make travelling at night that much more unsettling.
https://www.nexusmods.com/fallout4/mo...