use Google Tag Manager:
Are you tired of asking your web developer to add code, snippets, pixels or scripts to your site so you can track remarketing, conversions, analytics and more? Google Tag Manager (GTM) allows you to add or update tags without having to bother your developer.
Google Tag Manager gives you control over how your tags are defined and how they fire. GTM involves a little bit of a learning curve, but once you understand the basics, you'll wonder how you ever got along without it. If you're an SEO who hasn't yet delved into tracking codes (I know you're out there, and it's okay!), now's the time to start.
Using tracking code will help you measure the results of your marketing campaigns — essentially, you'll be able to show the results that your digital marketing efforts are making. And don't worry, you don't have to be a programmer to dig in. As an added bonus, you can use GTM to manage your clients' campaigns as well — all without having to log into the back end of their websites.