partner-contact/partner_contact_weight/views/res_partner_view.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

    <record id="view_partner_contact_weight" model="ir.ui.view">
        <field name="name">Partner Contact Weight</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="partner_contact_personal_information_page.personal_information"/>
        <field name="arch" type="xml">
            <xpath expr="//page[@name='personal_information_page']/group[@name='personal_information_group']">
                <label for="weight"/>
                <div>
                    <field name='weight' class="oe_inline"/>
                    <field name='weight_uom'
                           class="oe_inline"
                           placeholder="UoM"/>
                </div>
            </xpath>
        </field>
    </record>

</odoo>