Poltergeist in the office: disappearing items and falling objects

A couple of years ago we moved from the old office to a new one, closer to the city center. The building has 2 floors, there used to be a shop on the second floor, we didn't pay attention to strange sounds. Then the shop closed/moved — who knows, the boss rented the second floor too for that reason, now it's relatively empty and used as a storage for unwanted laptops, printers, furniture and everything that didn't fit on the first floor. We work alone, sometimes in pairs when it's crazy busy.
Since then, sitting on the first floor, you can clearly hear footsteps and some kind of rustling on the second floor, especially creepy when you realize there are no people there and the entrance is locked. We went and checked, found no one.
As for the first floor, it all started with things suddenly disappearing from sight. I was taping up a package with tape, got distracted for a second, and the tape is no longer on the table. I looked in all the corners, on all the tables. Decided maybe it somehow fell under the table, looked there too, found nothing. I'm telling you, I went cold inside when I looked back up at the table — saw the fucking tape right in front of my eyes, exactly where I'd left it before it suddenly disappeared. Errors of perception are out of the question, I looked there a million times while searching, but it definitely wasn't on the table. After that things kept disappearing too, but were found in completely random places.

Not long ago, working at the computer, from the printer (on top of it there's a work smartphone, AC remote, etc.) suddenly sharply fell, no, not fell, but rather, flew onto the desk — the work phone. It couldn't have slid off, everything is level, behind the printer is a wall. A clear feeling as if someone deliberately fucking chucked it somewhere far, even allowing for the possibility of sliding, it couldn't fly off so sharply. I think, alright, put it back where it was — same shit a couple minutes later, fell again. And so several times, the most paradoxical thing, at some point I decided to see what was going on. When you watch — nothing happens, as soon as you look away — some fuckery starts and it falls again. I'd think I was losing it, but when I was off, I got a message from a coworker that a little mirror suddenly flew off her printer and she herself didn't understand what the fuck happened.
Now we work as we did, we already joke about it, these situations don't happen every day, but they do occur. Besides things disappearing/flying, only idiotic sounds nearby have been added, also of unclear origin, the last one sounded like a puff on an e-cigarette.