There are many ways and tools to hide or protect important data on a USB Flash Drive.However a simple format of the USB Flash Drive can erase the important data.
Using Fbinst, a hidden partition can be created to store important data.This hidden partition stays even after formatting the USB Flash Drive.

Fbinst is a really good USB Flash Disk formatting tool.However there are no deb or rpm packages for Fbinst.So you have to compile it from the source to use it in Linux.

Fbinst is a USB Flash Drive Formatting tool.It can create universal bootable USB Flash Drives which can be booted on different BIOSes.It creates a special disk layout on your bootable USB Flash Drive making it more compatible with old and troublesome BIOSes.