There’s only one dash cam worth considering and that’s the Blackvue 750 2C and you’ll need to have it hard wired to your car battery so it can work in Parking Mode. I’ve been through all this and I know what I’m taking about. There is a very helpful chap at Dashcams Australia and you can get one fast on-line but you may need to get an auto electrician to help install it.
Also as JimmyT says, tell everyone and I also suggest put an item on your next AGM asking for CCTV to be installed and meanwhile right now, officially in writing, ask your Executive Committee to do this or your Strata Manager. Just getting such a request may have the desired effect of making the psycho stop.