Want to know every device that’s logged into your iCloud account? It’s a breeze to find out—and may assuage any fears you have that someone has tapped into your accounts. In these uncertain times, the Mac 911 mailbox routinely hears from readers who worry that something is up. You can put at least one fear to rest by checking that iCloud device list. (Most recently, someone wondered if an unknown party was inserting entries into the Reading List.)
Nobody can gain access to any of your iCloud information without physical access to your devices, the ability to log in with your account information at iCloud.com (for limited kinds of data) or iCloud for Windows (even more limited), or by logging in to an Apple device with your Apple ID.
Read more at Macworld.com