Thankfully, it was still outside
This metal object doesn’t seem too alarming. It looks like it must’ve fallen out of something at one point, and whoever lost it doesn’t miss it. However, the truth behind the object and what it does is actually a pretty huge cause for concern.
This is a tension wrench, which people, usually locksmiths, use to pick locks. The OP found this piece left outside of their door one day and had to know what it was. After learning what it was, the OP’s paranoia probably went through the roof. Does this mean that someone tried to break into their home?