This question already has an answer here:
I have an UbuntuServer installed and filled with packages that I need, and it's ready for work.
Can I make a distro from VirtualBox image of UbuntuServer in to
.iso installable file with all the packages that I have setted up?
EDITED: I am sking how to create a distro from Virtual Machine and not how to convert Physical Machine in to Virtual machine.