#define BUTTON_PIN D2 // The ESP8266 pin connected to button's pin
#define BUZZER_PIN D1 // The ESP8266 pin connected to Buzzer's pin

void setup() {
  Serial.begin(9600);                // Initialize the Serial to communicate with the Serial Monitor.
  pinMode(BUTTON_PIN, INPUT_PULLUP); // Configure the ESP8266 pin to the input pull-up mode
  pinMode(BUZZER_PIN, OUTPUT);       // Configure the ESP8266 pin to the output mode
}

void loop() {
  int button_state = digitalRead(BUTTON_PIN); // read new state

  if (button_state == LOW) {
    Serial.println("The button is being pressed");
    digitalWrite(BUZZER_PIN, HIGH); // turn on
  }
  else
  if (button_state == HIGH) {
    Serial.println("The button is unpressed");
    digitalWrite(BUZZER_PIN, LOW);  // turn off
  }
}