$ sudo apt-get update
$ sudo apt-get install php-phpdocx 

php-phpdocx is installed in your system.

Make ensure the php-phpdocx package were installed using the commands given below,

$ sudo dpkg-query -l | grep php-phpdocx *

You will get with php-phpdocx package name, version, architecture and description in a table

php-phpdocx package basic information: