$ sudo apt-get update
$ sudo apt-get install fcitx-hangul 

fcitx-hangul is installed in your system.

Make ensure the fcitx-hangul package were installed using the commands given below,

$ sudo dpkg-query -l | grep fcitx-hangul *

You will get with fcitx-hangul package name, version, architecture and description in a table

fcitx-hangul package basic information: