You need a device called a transducer. This is measuring device that lets you calculate things like electricity. Never try and measure electricity yourself without an expert, as the results will be shocking 😉
You can measure certain electrical quantities such as voltage with a voltmeter or current with an ammeter or resistance with an ohmmeter! Sometimes these can all come together in a little thing called a multimeter, but you have to be careful in choosing the range you set it to. That means you will need to have a guess – timate of what your current/voltage/resistance value will be before you set out to accurately measure it.