The instrument used to measure forces in newtons is called a force sensor or Newton meter.

Here are some other names you might encounter:

* Force gauge

* Spring scale (though these usually measure in grams or kilograms, which can be converted to newtons)

* Load cell (these are often used for more precise measurements)

It's important to note that while these instruments measure force, they may display the measurement in different units. Always check the instrument's scale to be sure you are reading the force in Newtons.