I found solution which is working:-
first of all it was my mistake that I created `~/.Xcompose` instead of `~/.XCompose`
Install uim (Universal Input Method) Add `export GTK_IM_MODULE="uim"` to `~/.profile` Restart the gnome-session Now custom compose key sequence defined in `~/.XCompose` is working fine. Note that `export GTK_IM_MODULE="xim"` is not working.
