http://esp8266.github.io/Arduino/versions/2.3.0-rc2/doc/boards.html#nodemcu-1-0
The pertinent info is:
The board also features a NCP1117 voltage regulator, a blue LED on GPIO16 and a 220k/100k Ohm voltage divider on the ADC input pin.
Full pinout and PDF schematics can be found here
If you do not wish to modify your A0 voltage divider on the NodeMCU, then you must work with the two SMT resistors on the board and calculate the A/D readings appropriately.
Ray