Question

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Answer 1

for example you can use a dynamometer.
You can place that dynamometer at the place where you want to measure the electric field strength. Please keep in mind that the dynamometer will measure the magnitude of the force exerted on your test charge, so you have to divide that value, by the electric charge of your test charge

Answer 2

Or you can build a simple field strength meter (FSM) such as the one shown below.