You can Z-Wave and ZigBee devices which can do that. Monoprice used to make some earlier, you can check our ZooZ switches, they also have some devices or the NeoCam Mini Plug.
SmartThing drivers are very basic and AFAIK they don’t provide voltage measurement. They don’t even support current measurement officially so no way they can provide that, it’s something we’ve implemented as a custom capability. Hopefully they’ll make it standard in future, it’s a request we’ve been asking them for a while now.