Hey,

to develop a new widget have a look at: https://www.odoo.com/documentation/10.0/reference/javascript.html. Look also at the widget monetory in the 'web' module. 

Besides, you may achieve it simplier: just by using html tags. E.g.:

<div class="oe_inline">

     <field name="some_metric" class="oe_inline"/>

     <field name="some_uom" class="oe_inline"/>

</div>

where 'some_uom' is a char field related to uom_id short name