TL:DR I wanna scare the shit out of intruders, do you recommend Arduino or Raspberry Pi?

So, I live in a place kinda like a college, but everyone get their own room. There's staff 24/7, and obviously, I really dislike some of them. Otheres I just like to joke with.

Sometimes, I've thought of putting together a "system" which will probably make them shit a brick.
The way I would do this, is have an Arduino or Raspberry Pi connected to a sensor, which will trigger an airhorn somehow. Yes, and airhorn. They should shit bricks, remember?

That's the beginning tho. Later, if this ever becomes something, I plan on adding some system so it wont trigger when I open the door, along with flashing red lights when intruders opens the door.

I attached a picture. The smaller rectangle is my closet. First circle is the sensor, which I assume can just tell when the door moves, if I place it correctly.
The rectangle is the Arduino or Raspberry Pi, which should control it all as you probably already know.
The second circle is the airhorn. Not sure how I'm gonna trigger that yet.

So, does any of you have some advice or recommendations on how I can make this dream become true? Or even additional components to make it more efficient?
Last and most importantly, would Arduino or Raspberry Pi be best for this, is there a specific model thats better fit?