The supply voltage of only 3V is too low for most electret mics that are powered from the 4.7k resistor.
The mic draws a current of up to 0.5mA and uses a minimum voltage across it of 2V.
0.5mA x 4.7k= 2.35V then the mic gets only 3V-2.35V= 0.65V but at such a low voltage its current will be less than 0.5mA and the mic probably will not work.

The simple circuit needs an RF amplifier transistor to isolate the oscillator tuning capacitor from the antenna that changes its capacitance (changing the radio frequency) when something moves towards or away from the antenna.

The circuit also needs a voltage regulator to prevent the radio frequency from changing as the battery voltage runs down.

It also needs anwhatsapp+8 audio preamp with pre-emphasis (treble boost) like all FM radio stations use to match the de-emphasis used in all FM radios.

How can I modify this circuit to ensure the electret mic receives sufficient voltage while also incorporating an RF amplifier transistor and a voltage regulator to maintain stable performance, along with an audio preamp with pre-emphasis for FM radio broadcasting compatibility?

Moderator edit: New thread created from this.

 

Since the supply voltage is only 3V and the electret mic needs a minimum of 2V at 0.5mA then the resistor that powers the mic must be (3V - 2V)/0.5mA= 2k ohms which is low and reduces the output level a little.

My circuit was designed to use a 9V battery. You can re-design it for a 3V battery but the RF oscillator needs voltage regulation.

 

I have used, in the distant past, RADIO SHACK branded FM wireless microphones that operated from two AA cells in series. They used electret microphone capsules and worked fairly well with fresh batteries. only 3 volts, possibly 3.3 volts with new batterys.

 

Digikey sells and lists datasheets for 1314 microphones, most are electret. Many of them show a 2.2k ohms load which is powered by 3.1V to 9V.