They also make a flexible retreiver with a tiny 'claw' that is actuated by a cable. I see these everywhere.
I have another that is like a magnet on the end of an antennae.
Duct tape a length of small rubber or plastic tubing to a shop vac.
Sometimes you can grasp things with the suction.
If all else fails, put a 'rare earth' magnet on your string. These are super powerful, and not likely to let go once stuck on.
1986 300E 5-Speed 240k mi.