[Vuejs]-Vue / Buefy Datetimpciker: How can I submit the results of an vue compontent to a form?

You should bind datetimepicker to a variable normally with v-model, then assign that variable to a hidden input field.

In HTML file

<input type="hidden" name="mydate" value="{{ mydate }}" />
<b-datetimepicker
    v-model="mydate"
    ...>
</b-datetimepicker>

In JS file

data() {
    ...,
    mydate: null
}