If you are working with a version of Photoshop/Camera Raw that is older than your version of Lightroom, then Lightroom will create either a PSD or TIF file and send that to Photoshop. The file format is chosen in your Lightroom preferences. I think it's important to understand that even if Lightroom and Photoshop/Camera Raw are at the same level you can't actually work with the raw image data in Photoshop. By the time the image is opened in Photoshop it has been converted and is no longer raw image data. The only difference is that the PSD or TIF file is saved at the end of the Photoshop session rather than before Photoshop is used.
Once the Image is opened in the Photoshop you can go to filter and select Camera Raw Filter. The image will open in Camera raw