Add following code in theme’s functions.php file.
add_action( 'show_user_profile', 'extra_user_profile_fields' );
add_action( 'edit_user_profile', 'extra_user_profile_fields' );
function extra_user_profile_fields( $user ) { ?>
<table class="form-table">
<tr>
<th><label for="address"><?php _e("Designation"); ?></label></th>
<td>
<input type="text" name="designation" id="designation" value="<?php echo esc_attr( get_the_author_meta( 'designation', $user->ID ) ); ?>" class="regular-text" /><br />
</td>
</tr>
<tr>
<th><label for="city"><?php _e("Linked In"); ?></label></th>
<td>
<input type="text" name="linked_in" id="linked_in" value="<?php echo esc_attr( get_the_author_meta( 'linked_in', $user->ID ) ); ?>" class="regular-text" /><br />
</td>
</tr>
<tr>
<th><label for="province"><?php _e("Phone Number"); ?></label></th>
<td>
<input type="text" name="phone" id="phone" value="<?php echo esc_attr( get_the_author_meta( 'phone', $user->ID ) ); ?>" class="regular-text" /><br />
</td>
</tr>
</table>
<?php }
add_action( 'personal_options_update', 'save_extra_user_profile_fields' );
add_action( 'edit_user_profile_update', 'save_extra_user_profile_fields' );
function save_extra_user_profile_fields( $user_id ) {
if ( !current_user_can( 'edit_user', $user_id ) ) { return false; }
update_user_meta( $user_id, 'designation', $_POST['designation'] );
update_user_meta( $user_id, 'linked_in', $_POST['linked_in'] );
update_user_meta( $user_id, 'phone', $_POST['phone'] );
}