The following command will write a downloaded .iso file of your favourite distro to a USB stick. You can then boot off it and install to hardware.
sudo dd bs=4M if=./manjaro-xfce-18.0-stable-x86_64.iso of=/dev/sdb status=progress
Note that in my example, there was no partition on the usb stick to start with. I’d removed it using gparted (not necessary though).