Mercury does not make ANY engines that are compatible with NMEA-2000. The closest they get is their own, proprietary, closed standard called Smartcraft.
If your Mercury engine supports Smartcraft you can get a Mercury GATEWAY which will convert some of the data to NMEA-2000. This will cost about $700 and you may need to have a Smartcraft gauge to configure the GATEWAY. Find a Mercury dealer that knows about this sort of gear--most do not--and get their advice.
If your Mercury engine does not support Smartcraft, you will have to invent your own adaptation by buying a generic engine analogue data to NMEA-2000 data CONVERTOR, figure out how to wire it up to your engine, figure out how to calibrate all the sensors, and then see some of the data on your NMEA-2000 network. One device known to work reasonably well is the NOLAND RS11 convertor. See
http://www.nolandeng.com/rs11.php