A microphone has a tiny output level of about 10mV when 10cm away from your mouth and you are talking at an ordinary conversation level. A preamplifier with a gain of about 100 to 300 is needed for the preamp to drive a recorder or a power amplifier.
There are a few different types of microphones:
1) Dynamic, has a coil and magnet like a little loudspeaker.
2) Electret condenser, that has a Jfet impedance converter inside that must be powered with about 400uA at a few volts.
A hobbyist can connect a mic to the input of an LM386 little power amplifier set to a gain of 200 as shown on its datasheet. The cable between the mic and preamp or LM386 must be shielded audio cable to shield away mains electricity hum and other interference.