It sounds like you may have valid concerns, but I hope you understand that I do not believe other redditors are overreacting by... well, thinking you may not be thinking clearly here.

I do not mean to be critical at all, just to give it to you straight.

It is unreasonable for your neighbor to have dug a tunnel. Anything they would want to accomplish by digging a tunnel could be done by, I don't know, breaking a window of yours. A tunnel would be a ridiculously expensive endeavor for, well, basically anything less than millions of dollars in payout.

When it comes to tracking devices in a cell phone: this would just be done in software. There are "spyware" apps and this can be done by anyone who wants to badly enough.

I recommend two things.

One, get a new phone if you believe you have valid concerns, and get rid of the old phone.

And two, find someone you can speak to in confidence about this. That could be a therapist- it sounds like you're very stressed and it might be a good idea regardless. (I've had good experiences for anxiety myself.)

But it could also be a family member or close friend, it just needs to be someone you can talk to frankly with.