Whatsapp has new Security Update, a two-step verification to its security settings.This new feature prevents someone else from activating your phone number without a six-digit passcode.
Just this morning, the update was made active on Android. And it is also available on iOS and Windows. So to activate it, go to Settings, Account, Two-step verification, Enable.
After that, you’ll be asked to set a 6-digit passcode and an email address that will be used to reset your passcode in case you forget it. Although WhatsApp says it will prompt you to enter your code from time to time in order to help you remember it.
Once you do all of that, no one will be able to verify your number without your passcode.