Back in February, Microsoft introduced Hyper-V support for ARM64 PCs, something that was one of the key limitations at the time of Windows on ARM's launch. The only problem was that there was no way to actually spin up a Windows 10 virtual machine, because Microsoft doesn't make ARM64 images available.
Now, that's changing, at least for virtual machines. The firm released Windows 10 Insider Preview build 19624 as a VHDX for ARM64 PCs today, as the Windows Insider team teased yesterday. It probably goes without saying, but you cannot use this with x64 hardware.
There are also some prerequisites. Obviously, the use of Hyper-V means that you'll need to be running Windows 10 Pro or Enterprise. This is worth noting since pretty much every Windows on ARM PC has shipped with Home, other than the old Snapdragon 835 PCs, and the Surface Pro X for Business. That brings us to the next limitation, which is that Snapdragon 835 PCs are not supported. According to the download page, you need a Snapdragon 850, Snapdragon 8cx, or Microsoft SQ1. Presumably, the Snapdragon 8c will be added to this list whenever it comes to market.
Once you've got that done, you can download the VHDX here. If you upgrade your PC from Windows 10 Home to Pro in order to do this, make sure to activate Hyper-V in Settings.