If you want to customize the MariaDB version and I assume upgrading to a newer version is what you mean, you can follow Debian's/MariaDB's instructions to upgrade MariaDB. This is often done by creating the version specific sources.list file with the newer version. Then, simply run apt-get update and apt-get upgrade to get the newer version. At least, that worked for me in the past.
Please always try this in a testing environment first and make sure to backup your databases before attempting any upgrade.