How to install Metasploit and Armitage
Here is a blog post (untested but states it works for 16.04): http://www.darkoperator.com/installing-metasploit-in-ubunt/
OR
Install metasploit you can use automated installer:
64 Bit:
wget https://downloads.metasploit.com/data/releases/metasploit-latest-linux-x64-installer.run && wget https://downloads.metasploit.com/data/releases/metasploit-latest-linux-x64-installer.run.sha1 && echo $(cat metasploit-latest-linux-x64-installer.run.sha1)' 'metasploit-latest-linux-x64-installer.run > metasploit-latest-linux-x64-installer.run.sha1 && shasum -c metasploit-latest-linux-x64-installer.run.sha1 && chmod +x ./metasploit-latest-linux-x64-installer.run && sudo ./metasploit-latest-linux-x64-installer.run
(for 32bit version, same command but remove '-x64' from the filename/url)
Note
This should be ran on a virtual machine, dont ignore ssl errors/hash checksums (both are checked using the above script to ensure files being downloaded are from metasploit.com).
if wget failed makes sure you are using wget-ssl.