Apple has released second beta of an upcoming OS X 10.11.6 El Capitan update to developers for testing purposes. It can be downloaded through the Apple Developer Center or the Software Update mechanism in the Mac App Store.
Apple has also seeded the second beta of an upcoming iOS 9.3.3 update to developers for testing purposes. It can be downloaded from the Apple Developer Center or over-the-air with the proper configuration profile installed.
tvOS 9.2.2 and watchOS 2.2.2 betas are also available for developers.