What I refer by this is that this could potentially change the entire playstyle of spy.

First off, let's say it's not a sapper, it doesn't destroy sentries, but what it does is that you can plant this in a wall and benefit your team.

When you set it in a wåll, the device will start giving the location of enemy players in the nearby area, excluding invisible spies, and to better improve on this, the nearby sentries will have a tendency to shoot at specific areas where it believes there are enemies but there are none, want to make it better? The spy is given a laser sight tool, not a weapon, that with left click will make a fake signal of an enemy in the place its pointing at, but this effect can only happen when near the device radius, and with right click you destroy the device entirely.

and so you can put this, for example, right below 2forts farm zone (the one where you can enter from 4 places, 2 of which are accesible to each team respective, and there's 2 sets of stairs), you put one right below the sentry, and you aim at any place where the sentry is looking at and, while you don't destroy it directly, you use it against the engineer. 3 sentries in that spot, 3 engies that don't stop from coming, you disguise as an enemy and then make the sentries aim at the engies and now you can get rid of them.

Or just get rid of the concept of killing yellow-hatted engies and allow your team to see where the enemies are in that area while also nullifying the sounds a lot. I was thinking that you could summon a bot that pretends to be a teammate and you can shoot enemies with that bot, and when it dies you come back to the spot where you left the machine.

Yes, it could be destroyed with melee hits, by any class...