int analogPin = 12; // potentiometer wiper (middle terminal) connected to analog pin
                    // outside leads to ground and +5V
int val = 0;  // variable to store the value read

void setup() {
  Serial.begin(9600);           //  setup serial
}

void loop() {
  val = analogRead(analogPin);  // read the input pin
  Serial.println(val);          // debug value
  delay(1000);
}

esp:VIN
esp:GND.2
esp:D13
esp:D12
esp:D14
esp:D27
esp:D26
esp:D25
esp:D33
esp:D32
esp:D35
esp:D34
esp:VN
esp:VP
esp:EN
esp:3V3
esp:GND.1
esp:D15
esp:D2
esp:D4
esp:RX2
esp:TX2
esp:D5
esp:D18
esp:D19
esp:D21
esp:RX0
esp:TX0
esp:D22
esp:D23
pot1:GND
pot1:SIG
pot1:VCC