Someone logged in to the device with an Apple ID that is made to my email, but I didn't create it...

Someone logged in to the device with an Apple ID that is made to my email (I used this email for my current Apple ID before, but I changed it a year ago). I changed the password for this Apple ID, but I can't access it through security questions, because these security questions are not mine, but those of another person.

How is it possible that someone can create an Apple ID with my email adress without access to my email? I change my passwords regularly and checked my logged-in devices, so I know I'm the only one who has access to my email.

What should I do? Is there any way to cancel or access this account?