You know that ancient 90s alarm clock radio stashed in your basement? Put it on AM, turn it to the upper end of the dial where there's no stations (lower end tends to have a lot of sporadic noise from appliances and electric fields) and put it on a barely audible volume. Instant white noise generator.
Weirdly enough, that's kind of how I found out I had tinnitus. I had my headphones on and got bothered with the high pitch static sound, but when I went to unplug it, I found it wasn't even connected to any device.
Have you tried unplugging any chargers or electronics? Thought I had tinnitus for the longest time, until I realized the sound was coming from my outlet, and unplugging the brick solved the problem.