Enable Developer mode.

Then go to --> Technical Menu

Please set the decimal accuracy of UoM

You can modify Unit of measure for for products. But the this will show every where UOM is used and displayed. Like stock, purchase, sales, product, invoices etc.  That might be something you do not want. 

Odoo only support BOM defined by 1 pc. Instead define the BOM by 1000 Meter (Meter in our case).  And then we also can define components used by 1000 Meter.   This works straight good for calculation in Manufacturiong order for how much you need for components.  But if you use operations with work orders you get a problem ,as duration calculation is based on time for 1 pcs.

So we developed an automatic action to override the calculation of duration of operation.  Be aware that this include some custom fields in the work order.  Se screenshot of the action definition.

Where do I find this? I do not see the "technical" tab