sudo apt install build-essential dkms linux-headers-$(uname -r)
wget -q https://www.virtualbox.org/download/oracle_vbox_2016.asc -O- | sudo apt-key add - wget -q https://www.virtualbox.org/download/oracle_vbox.asc -O- | sudo apt-key add -
sudo add-apt-repository "deb http://download.virtualbox.org/virtualbox/debian bionic contrib"
sudo apt install virtualbox-6.0
Download VirtualBox Extension Pack
sudo VBoxManage extpack install --replace Oracle_VM_VirtualBox_Extension_Pack-${LatestVirtualBoxVersion}.vbox-extpack
References
https://tecadmin.net/install-virtualbox-on-ubuntu-18-04/
https://www.virtualbox.org/wiki/Downloads
https://download.virtualbox.org/virtualbox/
https://www.tecmint.com/install-virtualbox-guest-additions-in-ubuntu/