I hope you have already done Armature creation. If not you need to do that first. Components in MORSE are either robots, sensors or actuators. Robots are mainly containers for sensors and actuators. Assuming you already have an initial simulation environment called mysim, you can create a new sensor with:
$ morse add sensor <name> mysim
or, for actuators:
$ morse add actuator <name> mysim
Also I guess you are using Python. You need to implement a sub-class of morse.core.sensor.Sensor, respectively of morse.core.actuator.Actuator.
from morse.core.sensor import Sensor
_name = "MyImageSensor"
_short_descr = "A custom Image Sensor"
You can know more on how to add more components from here. Also please note that Armature Pose sensor must be added as a child of the armature you want to sense. You can see an example source code here .