A short cable that allows wired headphones with the traditional 3.5mm mini-phone connector to plug into the Lightning port ... Apple eliminated the analog headphone jack. See mini-phone connector.
That was the same year they killed the iPhone's headphone jack, bundling in a Lightning adapter for everyone's 3.5mm earbuds. Even if you praise Apple for being forward-thinking in adopting USB-C ...
In 2016, Apple released the iPhone 7 without a headphone jack. It only had the Lightning port ... you have to buy a dongle or an adapter. If you wanted to use your new MacBook for everything ...