The follower is sent back to their original location (i.e. Jericho to Megaton), however, they'd still be holding it, and you can retrieve the objects by gaining them as a follower again.
what if i hired Fawkes on my way to the other follower?
You can only have one companion, so to get your stuff you'd have to ditch Fawkes.
If you have Fawkes as your follower he'll trade it all for a Gatling Laser. He'll meet you when you get out of Raven Rock, however.