Hi. I am getting a message on my iPad saying it’s a security message and that my computer has been locked and I must call support to unlock

Scam. Apple will never contact you directly with an unsolicited message.

See >>> Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

If you are unsure of the source or provenance of a message or alert, do not respond to, or engage with, the message. Certainly do not, under any circumstances, attempt to contact anyone using the contact details that may have been provided within the message itself. If you need to verify a message from Apple, make independent contact with Apple Support.

Most scam alerts are designed to scare the unwary into giving away sensitive information - or to fool you into doing something that you shouldn’t - usually to defraud you financially.

Scam. Ignore it. Block the sender if possible.