Do you have separate outputs? If so, make a metronome buss and send to that output. You will also have to go into edit/project and make sure your metronome is set to go out the metronome buss you created.
Windows 10/64 bit/i7-6560U/SSD/16GB RAM/Cakelab/Sonar Platinum/Pro Tools/Studio 1/Studio 192/DP88/MOTU AVB/Grace M101/AKG Various/Blue Woodpecker/SM81x2/Yamaha C1L Grand Piano/CLP545/MOX88/MOTIF XS Rack Rack/MX61/Korg CX3/Karma/Scarbee EP88s/ Ivory/Ravenscroft Piano/JBL4410/NS10m/Auratones/Omnisphere/Play Composers Selection/Waves/Komplete Kontrol