$ sudo apt-get update
$ sudo apt-get install octave-openmpi-ext 

octave-openmpi-ext is installed in your system.

Make ensure the octave-openmpi-ext package were installed using the commands given below,

$ sudo dpkg-query -l | grep octave-openmpi-ext *

You will get with octave-openmpi-ext package name, version, architecture and description in a table

octave-openmpi-ext package basic information: