After connecting your microphone to a recorder, turn on the battery.
You should be able to hear your surrounding electromagnetic noise!
Note: If using headphones, be sure to lower the volume of your recorder before wearing it, as the sound from the microphone may be too loud and damage your hearing.
Ideas:  Try to use your microphone near electronic sources, such as washing machine, lamps, computer, telephone, wifi router.
Did you know that you can hear sounds with an EMF microphone underwater? Check out the videos!
The intriguing thing about recording EMF is that the frequency spectrum you get is much richer than what you get from a regular microphone (check the attached spectrogram).
This means that you can use extreme pitch shifts and get results that sound completely different from your original recordings.
Check out an example of some extreme pitch-shifted emf recordings on the attached .wav files, with which you can create music!