#define MAGNET_PIN 27

void setup() {
  Serial.begin(115200);
  pinMode(MAGNET_PIN, INPUT);
}

void loop() {

  int state = digitalRead(MAGNET_PIN);

  if (state == LOW) {
    Serial.println("Magnet detected");
  } else {
    Serial.println("No magnet");
  }

  delay(200);
}