Mojave guest OS on Yosemite Host via Parallels Desktop 10
Solution 1:
Here are the visualizers that I know about.
Parallels: Full version http://www.parallels.com/en/products/desktop/ fyi: Free version of Parallels for individual use: https://itunes.apple.com/us/app/parallels-desktop-lite/id1085114709?mt=12 Free version, if still available, will only work with the most current version of macOS.
VMware Fusion With VMware Fusion, run the most demanding Mac and Windows applications side-by-side at maximum speeds without rebooting http://www.vmware.com/products/fusion/
VirtualBox VirtualBox is free, but you get what you pay for. Works fine for non-macOS operating systems. Nightmare to get to work for macOS. Basically, you need to match a version of VirtualBox with a version of macOS that will work. "VirtualBox is a general-purpose full virtualizer for x86 hardware. " Runs Windows on Mac OS. http://www.virtualbox.org/