Most of the things that will be a common danger (that is too small to track) are tiny pieces of stuff. Think paint chips and sand grain sized objects. These can be from things that came off rockets and ships, and things we've left behind like experiments and satellites. When these tiny things intercept you at many kilometers per second it can be dramatic.

Anything larger, say a lost screw driver, would punch thru the ISS like it wasn't even there leading to some ugly consequences.

I did an internship at NASA. What they told me is that anything larger than a golf ball they track while anything smaller than, I think they said a penny, is too small to do damage. The problem is debris that's in between the two. In that case they only get a relatively short warning (it's been a while but I think it was on the order of a couple hours).

The ISS can dodge debris by adjusting the height of its orbit.

Bits of spacecraft falling off (Challenger's windshield was famously cracked by a paint chip), debris from satellite collisions, even anti-satellite weapons tests.

Debris from space. Lots of rocks are constantly falling from space from all over. Sometimes they're big and make pretty lights in the sky as they fall, often they are practically invisible.