dunst software package provides dmenu-ish notification-daemon, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install dunst
dunst is installed in your system.
Make ensure the dunst package were installed using the commands given below,
$ sudo dpkg-query -l | grep dunst *
You will get with dunst package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | X Window System software |
| Package | dunst |
| Version | 1.1.0-2 |
| Description | dmenu-ish notification-daemon |
| Sub Section | X153 |