Code

#include <Servo.h>

//define servos
Servo servo1;
Servo servo2;
Servo servo3;
Servo servo4;

//define potentiometers
int pot1 = A1;
int pot2 = A2;
int pot3 = A3;

//value variables
int valpot1;
int valpot2;
int valpot3;
int sensorValue;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
//Servo pin atttach
servo1.attach(3);
servo2.attach(5);
servo3.attach(6);
servo4.attach(9);

//servo base angle
servo1.write(0);
servo2.write(0);
servo3.write(0);
servo4.write(0);

//Button setup
pinMode(4, INPUT_PULLUP);

}

void loop() {
  // put your main code here, to run repeatedly:
  valpot1 = analogRead(pot1);
  valpot1 = map(valpot1, 0, 1023, 0, 180);
  servo1.write(valpot1);

    valpot2 = analogRead(pot2);
  valpot2 = map(valpot2, 0, 1023, 0, 180);
  servo2.write(valpot2);

    valpot3 = analogRead(pot3);
  valpot3 = map(valpot3, 0, 1023, 0, 180);
  servo3.write(valpot3);

  sensorValue = digitalRead(4);
  if(sensorValue == HIGH){
    servo4.write(180);

    }else{
       servo4.write(0);
     }

   delay(200);
}