how to convert text to Hexadecimal

hi guys.
how can i get a word from serial monitor and then convert it to hexadecimal and save it to an byte?
my code is not completed:

byte incomingByte [16];

void setup()
{
  Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
  Serial.println("hi. pls write a word :");
}

void loop()
{
  byte n = Serial.available();
  if( n !=0)
  {
    byte m = Serial.readBytesUntil('\n', incomingByte, 16);
    incomingByte[m] = '\0'; //add  null character

  }
}