I don't think InDesign directly exports to jpg
Only suggestion I have is to do a screenshot of it. If you only want a low res image then this will work fine.
If you require a higher res image then do the following:
Zoom in on a part of the page - take a screenshot
Move to the next part of the page - take a screenshot
Keep doing this until you have the whole page captured and then assemble the mosaic in a graphics application. You have control over the resolution of the image by choosing how much to zoom in for the screenshots. Doesn't take long.
Assume you know how to take a screenshot?
If not - just tap the PrtScn (Print Screen) key on your keyboard, then go to a graphics application and choose the paste command.
I have done this before with pagemaker documents and excel invoices etc and it works fine. Depending on how large you want the end result you may get away with just 2 screenshots for the top/bottom of the page.
EDIT: Or - export the IDD file as a PDF file and then open it in a graphics application that support PDF files.
e.g. PaintShop Pro - Photoshop - bound to be others