I live in an apartment, so I’m not allowed to have a security system. That said, I’ve found every loophole an apartment dweller can use for security. For starters, I have a dog… which gave me an excuse to put a pet gate outside my door to prevent him from escaping. I also have a ring doorbell. I’m not allowed to change my doorbell, but ring just came out with one that replaced a doors peephole, which is perfect since I had one. (I’m still able to use the peephole, too) I also have Amazon key, and while I wasn’t allowed to replace my deadbolt, Amazon has a solution for renter’s that only replaces the inside portion of the deadbolt, but leaves the outside the same, so my apartment manager can still gain access. That system also means I have a camera facing me door from the inside. I also have a camera in my living room, and looking out the window to my car.
What this all means is, I’m alerted anytime there’s movement outside my door, my doorbell is rang, my door is knocked on, my door is unlocked or locked, there’s movement in my dining room where the only entry door is, or there’s movement in my living room, which includes my 3rd floor balcony door. (I mostly use that camera to check on my dog while I’m at work)