https://forum.arduino.cc/index.php?topic=113921.0

#include <Keypad.h>

const byte ROWS = 4; //four rows
const byte COLS = 3; //three columns
char keys[ROWS][COLS] = {
  {'<','^','>'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[ROWS] = {5, 4, 3, 2}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {8, 7, 6}; //connect to the column pinouts of the keypad

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

char holdKey;
unsigned long t_hold;

void setup(){
  Serial.begin(9600);
}
  
void loop(){
  char key = keypad.getKey();
  
   if (key){
     holdKey = key;
     Serial.println(key);
   }
  
   if (keypad.getState() == HOLD) {
      if ((millis() - t_hold) > 100 ) {
          switch (holdKey) {
              case '<':
                  Serial.println("Move Left");
                  break;
              case '^':
                  Serial.println("Move Up");
                  break;
              case '>':
                  Serial.println("Move Right");
          }
          t_hold = millis();
      }
   }
}