Step 1: Import apt repository
Add repository key:
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 -
Step 2:  Add the VirtualBox repository
After importing the key, you can add the repository to the system using the command:
Ubuntu 20.04:
echo "deb [arch=amd64] http://download.virtualbox.org/virtualbox/debian eoan contrib" | sudo tee /etc/apt/sources.list.d/virtualbox.list
Ubuntu 18.04/16.04 & Debian 10/9:
echo "deb [arch=amd64] http://download.virtualbox.org/virtualbox/debian $(lsb_release -sc) contrib" | sudo tee /etc/apt/sources.list.d/virtualbox.list
Step 3:  Install VirtualBox & Extension pack
Finally, install VirtualBox & Extension pack on your Ubuntu 20.04/18.04 / Debian 10/9 system by running the commands:
sudo apt update
sudo apt install linux-headers-$(uname -r) dkms
sudo apt-get install virtualbox-6.1
Download Extension Pack:
cd ~/
wget https://download.virtualbox.org/virtualbox/6.1.6/Oracle_VM_Vir