$ sudo apt-get update
$ sudo apt-get install ibus-unikey 

ibus-unikey is installed in your system.

Make ensure the ibus-unikey package were installed using the commands given below,

$ sudo dpkg-query -l | grep ibus-unikey *

You will get with ibus-unikey package name, version, architecture and description in a table

ibus-unikey package basic information: