#include <Servo.h>

Servo myservo;
int switchPin = 2;

void setup() {
  myservo.attach(9);
  pinMode(switchPin, INPUT_PULLUP);
}

void loop() {
  if (digitalRead(switchPin) == HIGH) {
    myservo.write(180);
  } else {
    myservo.write(-180);
  }
}