If the Caps Lock key on your MacBook or MacBook Pro isn't working as expected
If the Caps Lock key on your MacBook (Retina, 12-inch, Early 2015), MacBook (Retina, 12-inch, Early 2016), or MacBook Pro (Retina, 13-inch, Early 2015) is working the opposite of how you expect, you can fix the issue by updating your Mac to the latest version of OS X.
When you log in to one of these Mac models, you might notice that the Caps Lock icon
appears in the password field, but the green light on the Caps Lock key is off.Your Caps Lock key might also behave the opposite of how you expect by allowing lower-case letters when its green light is on, or forcing all-caps letters when its light is off.
An out-of-sync Caps Lock key is most likely to occur at the OS X login screen when you're entering your password, and can be the result of rapidly toggling the Caps Lock key on and off.
This issue was resolved in OS X El Capitan v10.11.6, so update the software on your Mac to make sure you're running the latest version.