That depends on what kind of scary. Searching up the terms "ambient scary music" or "ambient creepy music" would seem like it'd do the trick. Maybe "ambient horror music" if that's what you're going for. Again, depends on the type of scary. Ambient type music would be creepy and suitable for background music. "Scary background music" would also likely give you some results.
Just open up Youtube and do a simple search . . .
Or click here - Youtube scary music list
Do you just want to just listen to it? Doubt that so most likely you are about to use this background music for your videos or something. That's not a good idea because your videos can be blocked as far as the music belongs to it's author or a company which represents the author. So I advise you to search for royalty-free music on soundhills.com for example.