PrisonMining is a lightweight PocketEdition plugin developed by JacksonML. It allows adminsitrators to jail players. To become free from jail, a player must break a certain number of blocks, set by the jailer.
Disclaimer: I am not responsible what this plugin may do to your world. No plugin is perfect, so PLEASE keep regular backups, even if you don't use my plugin. For me to fix a bug, crash, or any other problem, you must report it, with the crash report! Please use the issues tab in this github project.