Install zsh

apt install zsh
chsh -s /bin/zsh root
chsh -s /bin/zsh {username}

exit and login again

Go to oh-my-zsh website

Install on-my-zsh by following

sh -c "$(curl -fsSL https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"

change themes in ~/.zshrc, e.g. philips, or schminitz