latest eclipse(oxygen) is not available in Ubuntu repos(for 16.04 i think).You need to download it from here :- https://www.eclipse.org/
You can extract it anywhere but I suggest you to extract it in /opt.
sudo tar -xvzf eclipse-cpp-oxygen-R-linux-gtk-x86_64.tar.gz -C /opt
note:- the name
eclipse-cpp-oxygen-R-linux-gtk-x86_64.tar.gz can be different in your case.
then you need to make .desktop file which is shown here:- Create a .desktop file that opens and execute a command in a terminal
you can install eclipse by
sudo apt install eclipse and then upgrade to latest version from eclipse.