Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1200059

MacLeod's description:

Genre: Horror
Length: 5:52
Instruments: Synths, Percussion
Tempo: 80

Weird synth drone with a soundtrack-style percussion backing driver. ISRC: US-UAN-12-00059 Dark, Eerie, Intense, Mysterious, Suspenseful, Unnerving 2012