must be a scan   how does he know about my computer?

It is a scam and has been reported at 800Notes and a number of other places.  Your smartest move is to use caller ID and not answer if you don't recognize name or number.  If it is legitimate, they will leave a message.  They don't know anything your computer, they are just looking for gullible folks to scam.

Called but left no message.   Caller ID said  new york

Call from this number to our home number.  Scan to try to get you to give control of your computer to them so they can fix some sort of "technical problem".  I'm a senior systems engineer and have been tracking these scam groups, trying to shut them down.  Don't answer calls from this number, or if you do, tell them you realize that they are a theft ring and that you will turn their number over to the proper authorities.

Same as above, sort of,  I am just a programmer with over 30 years experience.  The above "Systems Engineer" is correct, they are trying to set malware on your computer.  If you do answer, do one of two things. Either just hang up as soon as you realize who they are. OR (my favorite) Play along for as long as you can keep them on the phone. Do not give permission to set a program on your computer of course.  I kept one guy on the line over 25 minutes before I told him the truth  His answer  *@#$%^&^%$#$%^&^%.  I can't print what he really said.