Magento2.2 - Send event to Google Analytics in a .phtml file

Question

I have tried to send an event in .phtml file using

<script>ga('send', 'event', {
    eventCategory: '...',
    eventAction: '...',
    eventLabel: '...'
});</script>

But Browser Console says that ga is undefined, Please help me how can I send an event to Google Analytics.

I will be very thankful to you.