#include <ESP32Servo.h>

Servo myservo;  
int potpin = 33;
int val;   

void setup() {
  myservo.attach(21);  
  pinMode(potpin, INPUT);
}

void loop() {
  val = analogRead(potpin);  
  val = map(val, 0, 1023, 0, 180); 
  myservo.write(val); 
  delay(15); 
}