$ sudo apt-get update
$ sudo apt-get install mod-gearman-module 

mod-gearman-module is installed in your system.

Make ensure the mod-gearman-module package were installed using the commands given below,

$ sudo dpkg-query -l | grep mod-gearman-module *

You will get with mod-gearman-module package name, version, architecture and description in a table

mod-gearman-module package basic information: