Vagrant repository probably not updated to the latest version, this is the reason that it always install older version when apt-get install vagrant
command is used.
The easiest way to pull and install latest version using terminal is to find the path to the .deb
file and install it using dpkg
You may get the list of all the vagrant
updates here,
https://releases.hashicorp.com/vagrant/
I got this as latest version from above archive,
https://releases.hashicorp.com/vagrant/2.0.4/vagrant_2.0.4_x86_64.deb
Once you have that link, delete previous version of vagrant
(if it is installed) as follows,
sudo apt-get remove --auto-remove vagrant
rm -r ~/.vagrant.d
and install newest version,
wget https://releases.hashicorp.com/vagrant/2.0.4/vagrant_2.0.4_x86_64.deb
sudo dpkg -i vagrant_2.0.4_x86_64.deb
Once done, you can verify if its successfully installed,
vagrant version