In order to comply with the coronavirus job retention scheme rules, you cannot require staff to work for you while on furlough. That position changed on 1 July, with a slight alteration to the scheme rules to allow employees to work part time and be on furlough at the same time. But that will mean a proportionate reduction in the amount of furlough reimbursement you can recover; ie you will be unable to claim furlough for any hours that the employee is working.
Of course, none of this prevents you keeping in touch with staff and engaging with them, and I really encourage you to do this. Many businesses have ‘keeping in touch’ schemes for other purposes such as maternity leave, and I encourage you to dust yours down and expand it during this period. Your communications should be informative and frequent – and also engage staff in any social connections you have set up.