How to trackEvent with more customed property?

In my Vue Project, I use matomo to track event, when I was using the API trackEvent, I wanna post more infomation to backend report.For examplae,when a user click the login button,I track this event and wanna post extral infomation.but I don’t know how to do this?

this.$matomo.trackEvent('index', 'click', 'loginBtn', {
property1: 'ffsfsfss'

You can use custom dimensions…
How do I use Extractions to track action data with Custom Dimensions? FAQ - Analytics Platform - Matomo