How to perform Change Detection for MODIS reflectance data

I’m trying to run Change Detection on MODIS band 6 (only!) from two different dates but can’t find the right tool for data analysis.
which tools do you recommend?

I’d say this depends on what kind of changes you want to detect.
There are approaches directly applies on the bands, there are change indices and there are post-classification methods.

I want to perform image differencing. I’m working only with band 6 data, and no indices are applied. The band math is not suited because it works only one product, and I want to see the change between two products. The images are in BEAM-DIMAP format. What are the recommended tools for this?

Band Maths can work on two product but they need to have the same size and must cover the same region.
If this does not apply to your data you can force this by collocating two products. This will merge one product into the other. Then you can do the difference calculation.

So how do I merge two bands into one product? (to have a new product with B6 of the two dates).
I appreciate your help!

You can use the collocation.
Specify the one as master and one as slave. (Yes, I know. The names are not good.)

Before you should do a subset, so that only the band 6 is included.

It worked! thank you so much!