i3lock, the go-to locker for i3wm, does not support unlocking with fingerprint scanners. Until now, that is :) To unlock your linux computer by simply scanning your fingerprint, install fprintd and then use this script instead of i3lock to lock your session:
i3lock &
(while pidof i3lock; do
if (fprintd-verify | grep verify-match); then
killall i3lock
fi
done) &