Creating imafge iso from USB

To create an image from a drive

sudo dd if=/dev/sdx of=/path/to/new.iso

Alternatively, to create a USB drive from an image

sudo dd if=/path/to/iso of=/dev/sdx

Replace /dev/sdx with your USB drive, e.g. /dev/sdc

Example of iso to USB:
dd if=/home/myuser/ISO/ready_USB_ISO/lubuntu16_i386a.iso | pv | dd of=/dev/sdd bs=4096


Convert bootable USB to ISO file - Ask Ubuntu