They make those small parts grabbers that you can use to fish small items from places they fell or you dropped them into. Sometimes that doesn't work.
What I found does work even getting into places the grabber things can't is to use a rubber hose with a strainer attached to the front and the other end hooked up to a good wet/dry vac. You can fish that plastic or rubber hose into places almost nothing else can get to and it will pick it up. The bonus is that it doesn't have to be metallic.
The strainer prevents really small items from going into the canister so you don't have to empty it first or dig through the grime.
For getting past tight curves, routing some string through the end of the hose, one length opposite another you can pull on the string and practically guide it almost anywhere.
Cheap and it works.
