Taking long exposure using our mobile phone may be impossible due to its less ability rather that DSLR/SLR Camera. You might also get messy result because we meant to have a shaky hand. But using the 3rd party camera and a stable/steady placeholder could make it possible.
Attach your device onto the tripod or mobile stand.
Next, go to Play Store and looking for Camera Steak then install.
Once done, try to open the app and set your exposure to hightlights. Then look for a perfect angle then focus the subject.
When you're ready, hold and long press the camera shutter until you get the right amount of data frame compressed. Then tap the check button to see the result.