I haven't used sensors but I can point you in the right direction.
The Solidworks API documentation isn't perfect but it does happen to be the exclusive resource for finding this sort of information out. I would recommend taking a look at it.
Every object in the API has an Interface page and a Members page in the documentation. If you want to find how to get a reference to a particular object, every method that creates it will be listed on the Interface page under Accessors. If you recursively trace the accessors backwards (in the documentation), you should eventually lead to the Solidworks application object that gives access to the API in vba. Meanwhile, the Members page will list every member and method available from that object. Usually a link to the members page is at the bottom of the interface page under See Also (and vice versa).
It looks like ISensors give get and set access to the sensor trigger value and the state so this is probably a good place to start looking.