Microsoft has introduced a new addition to its developer program known asPreview for Developers, which allows registered developers early access to the latest OS updates before they are released to the public. In order to take advantage of the preview, you'll need either a Dev Center account, an App Studio account or a phone that's registered and unlocked to developers.
Its important to note that these are early release builds and you will not be able to revert back to your previous software after updating your device. You also run the risk of bricking your device if you don't do things exactly right.