Hello @Rogério Ferreira
Here is brief information
- Your Microsoft account is the combination of an email address and password that you use to sign in to services like OneDrive, Xbox LIVE, and Outlook.com.
- Your Work or School Account is the way to enable personal devices to access work resources. It can be done via Settings or when the user configures an app for work. Azure AD Join allow users to sign-in/unlock devices using their work accounts.
Answering your question(Is it possible for this to happen without my knowledge and prior notice from Microsoft?)
It's very unlikely for your personal Microsoft account to be linked to a corporate Azure AD without your knowledge. There are consent processes and notifications in place when accounts are being added or when devices are being managed.
You need to accepted to join your device to the corporate intune or azure, the global admin won't be able to have access to it.
You can check this on your Windows OS if you suspect it's being managed by a corporate account:
- Open Settings.
- Go to Accounts.
- Look under the "Access work or school" section. You can see if your device is connected to any work or school accounts and if it's being managed by organization.