The simple cheap way to do this is to use something like the Saxon Scopepix smartphone adapter, it retails for less than $40 and if your phone has 3 camera lenses just adjust it to use the one that gives the best views. If in doubt about it fitting your phone just call the retailer and ask about dimensions of device.
For extra WOW factor you can also use a screen mirror app on your phone and send to a TV and take in the view on the big screen, this works well for the moon, planets and bright star clusters but not so well on dim objects like nebula.
With your Dob being a push to with no motor tracking system your options are limited as other dedicated astro photography systems require tracking and guiding to give good results.
Saxon Scopepix smartphone adapter
http://www.sirius-optics.com.au/saxo...e-adapter.html