Recently I have been searching around, trying to find Resource Packs that add new cave sounds. However, I couldn't find any so I took the task upon myself to make a pack like that myself and I did. I have had it only on my website for now, however I thought that if I published it somewhere like PMC then it would get more attention. This pack uses Freesound.

Credits:


Zimbot, Eerie Ambience 4


Mr_KeybOred - Eerie Alien Horn


PrankheitenEberex - Eerie Distant Rumbling Sound


DAN2008 - Eerie Ambiance


Razorrekker - Irregular Glass Clock


Figowitz - Midnight Church Bells Frederiksborg Castle


SamsterBirdies - Eerie Ambience


MoveAwayPodcast - Inexplicable noise at 4am


Audio_Dread - Creepy Monster Noise


cabled_mess - Deep 05 Engine Noise


Fission9 - Ambient Noise


SamsterBirdies - Horror Sting


NicknameLarry - "Escalator - Metro Noise"

You can listen to the sounds here:
freesound.org/people/StereoMadnesss/downloaded_sounds/