USB to increase RAM

[Carmel NY]

Windows has a feature called "ReadyBoost" that can use a USB drive to
increase RAM. I would like to do the same thing on my FreeBSD 12
machine. I have not been able to find any documentation specifically
dealing with that operation. Can anyone direct me to some or provide an
example of how to accomplish this? I have a 32Gb USB drive I want to
use for this purpose. Also, what would be the best file system to use.
I currently have ZFS being employed for the HD.

Thanks!

-- 
Carmel