There are a lot of different solutions/workarounds I'm going to mention some:
1. Find installed version
dpkg -l pkg-name to get package version, e.g:
$ dpkg -l firefox
it's going to give you some information:
||/ Name Version Architecture Description
ii firefox 53.0.3+build1-0ubuntu0. amd64 Safe and easy web brow
1.2. pkg --version
Depends on your package switches like
--version might be available to you:
2. Last available version
2.1. apt show
sudo apt update to make sure your sources are up to date, and use
apt show firefox | grep -i version to see the last version available.
2.2. Ubuntu packages database
You can also check https://packages.ubuntu.com to search for your package version.
2.3. apt changelog
As an alternative you can use
apt changelog pkg-name, e.g
apt changelog firefox this will connect to internet to get the last "change log" data so you don't have to update your sources for using this command.
The other option is
rmadison, it remotely query the archive database about a packages, so you don't have to update your source in this option.
First install its package:
sudo apt install devscripts, then use it like:
rmadison -s zesty -a amd64 wget
it give you last available version of
wget for "zesty" and "amd64" architecture.