CAD tip # 13000:

Normally, dynamic block parameters are just internal values that are not displayed in an inserted block (block reference). If you need to display them as text, you can add visible attributes to the block and link the geometric parameters to those standard block attributes.

You need the parameter to be visible as a property, i.e., the Properties palette in the block editor need to have the setting "Display Properties = Yes".

In the block editor (BEDIT), add a new preset attribute using the ATTDEF command and click the Insert Field button as its Default value. Select "BlockPlaceholder" from the list of field names and select the specific geometry parameter to be monitored from the list of block properties. Optionally, set its display format. Save the changes to the block.

To update existing (already inserted) blocks, you need to synchronize the new definition. Run the BATTMAN command, select the given dynamic block and click Synchronize.

After changing the dimension in the block reference, you will need to REGENerate the DWG drawing to reflect the changed parameter value in the label text.