The joystick measures the movement of a small arm on the X and Y axes.

When you want to provide user input with a joystick or track the movement of a plane (by attaching the plane of the joystick to it).

The joystick is essentially two potentiometers connected to a stick. As the stick moves left and right, it rotates the X-axis potentiometer. As it moves up and down, it rotates the Y-axis potentiometer. The entire joystick is also connected to a button so that the stick may be pressed inward.

Simply connect 5 volts to VCC, ground to GND, and feed each of the potentiometer outputs (Vrx and VRy) to two of the analog input lines on the Arduino. Both axes of the joystick are measured simultaneously. Additionally, the button (SW pin) may be connected to a digital pin with a pullup resistor.

/*
 * This program reads a joystick connected to JOY_X_PIN,
 * JOY_Y_PIN, and JOY_SW_PIN and sends the data back to
 * the computer via serial.
 *
 * Originally from: https://create.arduino.cc/projecthub/MisterBotBreak/how-to-use-a-joystick-with-serial-monitor-1f04f0
 * Modified 2021-01-19 by Perry Naseck
 */

const int JOY_X_PIN = A0; // Analog input pin for X movement
const int JOY_Y_PIN = A1; // Analog input pin for Y movement
const int JOY_SW_PIN = 2; // Digital input pin for button (pressing down on the joystick)

// Variables to keep track of the current positions and states
int joyXPos = 0;
int joyYPos = 0;
int joySWState = 0;

void setup() {
  // Setup serial port to send the joystick data back to the computer
  Serial.begin(9600);

  // Setup the joystick inputs
  pinMode(JOY_X_PIN, INPUT);
  pinMode(JOY_Y_PIN, INPUT);

  // The switch/button is just like a normal button, so
  // it needs a pullup resistor as well
  pinMode(JOY_SW_PIN, INPUT);
}

void loop() {
  // Get the current states
  joyXPos = analogRead(JOY_X_PIN);
  joyYPos = analogRead(JOY_Y_PIN);
  joySWState = digitalRead(JOY_SW_PIN);

  // Send the data over serial
  Serial.print("X: ");
  Serial.print(joyXPos);
  Serial.print(" Y: ");
  Serial.print(joyYPos);
  Serial.print(" SW: ");
  Serial.println(joySWState);

  // Delay to not send messages too fast
  delay(100);
}

• Arduino: How to Use a Joystick with Serial Monitor