Add javascript to header.php

Hi.
I have to add a javascript code to a header.php

How i do that? Thanks a lot.

This is the code:

<script async type="text/javascript" src="https://smart-home.com.co/JavaScript/LeadControlAPIV2.js"></script>
<script language="javascript" type="text/javascript">

document.addEventListener('click', function (e) {
if (e.target && e.target.id == 'idBtnEnviar') {
submitLeadForm(e, "hA/lvw9cX/9c0GBwnEspO8CP4sbd1qsSGftT-e/zcSQANn2BkZKWeATeX8v3sgbB");
}
});

function submitLeadForm(element, projectId) {

var elementButton = document.getElementById(element.target.id);
var form = elementButton.form;

const SH = new SmartHomeAPIV2(projectId);
var formData = SH.getFormData(form.elements);

const nameFields = ['form-field-name'];
const emailFields = ['form-field-email'];
const mobileNumberFields = ['form-field-field_1'];
const commentsFields = [['form-field-field_2','¿Qué te gustaría saber del proyecto?'],['form-field-message','Mensaje']];

var data = {
firstName: SH.getFieldValue(formData, nameFields),
lastName: '',
email: SH.getFieldValue(formData, emailFields),
mobile_number: SH.getFieldValue(formData,mobileNumberFields),
phone_number:'',
comment: SH.getMultipleFieldValue(formData, commentsFields),
origin: window.location.href

};
if (data.firstName == "" || data.email == "" || data.mobile_number == "") {
customAlert("Verifique los datos");
return;
}
SH.postLeadData(data, '');
}

</script>