const byte interruptPin = 14;
volatile byte state = 0;

void setup() {
  pinMode(interruptPin, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(interruptPin), INTR, FALLING);
  pinMode(2, OUTPUT);
  pinMode(4, OUTPUT);
}

void loop() {
  digitalWrite(4, !state);
  digitalWrite(2, state);
}

void INTR() {
  state = !state;
}