I don't believe that there is a simple way to extract the decomposition data from the TS Plot tool.
However, I have created and attached a macro that will retrieve the data I believe you are looking for.
The configuration for this macro is very similar to the TS Plot tool.
1. Select the target field
2. Select frequency
3. Select the period starting date (optional)
The output from this macro will contain the following fields:
3. The target field (Bookings in this example)
4. seasonal - the seasonal data points from the Decomposition Plot
5. trend - the trend data points from the Decomposition Plot
6. remainder - the remainder data points from the Decomposition Plot
This macro was developed using 11.7, so make sure you are using the latest version of Alteryx or else the macro won't load correctly.
Let me know if you have any questions or if you were looking for something different!
Customer Support Engineer