Google Forms Custom Subject Line

Question

I am new to Apps Script and I have found some great information on this site to automate an email with the form responses anytime someone submits a new Google Form Response. However, I want the subject line to be the answers they submitted for questions "Last Name", "Employee Number", and "Business Unit". I've tried to modify a few different answers from other questions here and I haven't been able to get them to work. I really don't want to use an add-on as this will have employee information. Below is the script I am using now. It works great, but I just need a way to change the subject line. Thank you all!

function createFormSubmitTrigger() {

  var form = FormApp.getActiveForm();

  var currentTriggers = ScriptApp.getProjectTriggers();
  if(currentTriggers.length > 0)
    return;
  
  ScriptApp.newTrigger("onFormSubmit").forForm(form).onFormSubmit().create();
}

function onFormSubmit(e) {
 
  var formResponse = e.response;

  var itemResponses = formResponse.getItemResponses();

  var emailBody = "New form response:\n\n";

  itemResponses.forEach(function(itemResponse) {
    var title = itemResponse.getItem().getTitle();
    var response = itemResponse.getResponse();
    emailBody += title + "\n" + response + "\n\n";
  });

  sendEmail(emailBody);
}

function sendEmail(emailBody)
 {
  MailApp.sendEmail("[email protected]", "subject", emailBody);