void setup() {
  // put your setup code here, to run once:
pinMode(12, OUTPUT);
Serial.begin(9600);
attachInterrupt(digitalPinToInterrupt(21),mil,RISING);
attachInterrupt(digitalPinToInterrupt(20),mic,RISING);
}

void mil(){
Serial.write("millis= ");
Serial.println(millis());
}

void mic(){
Serial.write("micros= ");
Serial.println(micros()); 
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(12, HIGH);
delay(500);
digitalWrite(12, LOW);
delay(500);
}