You can install rEFInd on the hard drive of your Mac or USB drive. If you want to create the USB will use a Mac computer first have to install a bootloader, rEFInd is an excellent bootloader that supports Mac OS X (El Capitan), Windows and Linux.
There are unofficial distributions calls Hackintosh. The OS X is an operating system very jealous and hardly does boot on any computer that is not a Mac.
