You can record on your phone as this will give a good recording.
However, if you want a high quality recording and have got the money to pay for it then then you need to get your own music recording equipment.
Type of microphone
There are 2 main types of microphones
-Dynamic Microphones (Best for singing)
-Condenser Microphones (Best for instruments)
Why? - The condenser microphones are better because they can take the higher range of the piano whereas the dynamic microphone isn't able to do this as well.
I have got the following music recording equipment which isn't too expensive:
Audio Technica 2020 Microphone
I use this microphone for recording piano and for my online music lessons.
Price - £71.50 - This is very cheap for a quality microphone. Link available at musicmatter.co.uk/audio-technica-at2020-condenser-microphone?gclid=Cj0KCQjw37iTBhCWARIsACBt1IyHzH-KWt6M3s1W3ZRPV8w_zwItNw3NXWy0Ic56yiUtcszRX_EI_EYaAgP3EALw_wcB
Sound - This microphone sounds very clear and like your actually in the room with the audio recording.
Durability - The only negative with this microphone is that you have to be very careful when using it so make sure that the microphone isn't going to move when recording it as it can break easily.
The best place to place your microphone for the piano is behind the piano for a brighter sound. The 2nd best place to put is directly above the piano lid.
In my videos I don't have access to either of these so I place it about 6 human feet away from the piano so that the piano isn't too loud. Putting the piano in front of the piano makes a truer sound.