Hi,

Yes, you can export and import your custom field in contacts.

Example:

Python:

from odoo import fields, models


class ResPartners(models.Model):
    """Inheriting the res. partner for adding the KYC details
    and corresponding states"""
    _inherit = "res.partner"


    x_custom_field = fields.Char(string="Custom Field")

XML

<record id="view_partner_form" model="ir.ui.view">
    <field name="name">res.partner.view.form.inherit</field>
    <field name="model">res.partner</field>
    <field name="inherit_id" ref="base.view_partner_form"/>
    <field name="arch" type="xml">
        <xpath expr="//field[@name='vat']" position="before">
            <field name="x_custom_field"/>
        </xpath>
    </field>
</record>

Result

Export the record:

Excel sheet:

Changed the value of the custom field 

Import the sheet

Hope it helps.