Should work fine in Xubuntu 18.04 which uses xfce4-pulseaudio-plugin by default (support for the XF86AudioMicMute key was added in version 0.3.0).
Should work fine in Xubuntu 18.04 which uses xfce4-pulseaudi o-plugin by default (support for the XF86AudioMicMute key was added in version 0.3.0).