José Adorno/BGR The iPhone has been around since 2007, and while it's a powerful device on its own, adding accessories can make it an even more useful product. For example, some companies create dedicated camera lenses, fast-charging power banks, and even  great 3-in-1 wireless chargers  for the iPhone – not to mention  the legion of MagSafe gadgets available . However, you can also greatly improve your iPhone's capabilities by adding Bluetooth accessories, like wireless headphones, an Apple Watch, or a smart water bottle. These devices can make your iPhone a lot more useful. Wireless headphones let you listen to music or join calls while your iPhone is charging; the Apple Watch tracks your health even when you're sleeping; and a Bluetooth bottle shows if you're drinking enough water throughout the day. Unlike many years ago, there's no need to turn off Bluetooth on an iPhone when you're not using it, or on any other tech product.…