This is an updated version that was made by Neo-Oli, instead of using 19.04 I've changed it to 20.04
You need to install git and proot in Termux before using this script.
pkg install git proot
git clone https://github.com/GYKgamer/Termux-Ubuntu
cd Termux-Ubuntu
chmod +x ubuntu.sh
./ubuntu.sh
termux-setup-storgae
After running it you can run "./start-ubuntu.sh" to switch into your ubuntu